Azo dyes with a coupling component of the aminothiazole series

ABSTRACT

Azo dyes of the formula ##STR1## where D is the radical of a diazo component of the aniline series or the series of the aromatic heterocyclic amines, 
     R 1  and R 2  are each C 1  -C 10  -alkyl, which may be substituted, C 5  -C 7  -cycloalkyl, C 3  -C 4  -alkenyl, substituted or unsubstituted phenyl, or are together with the nitrogen atom joining them together a heterocyclic radical, and 
     R 3  is tert-butyl or tert-pentyl, 
     are useful for thermal transfer and for dyeing or printing synthetic materials.

This application is a 371 of PCT/EP95/02866 filed Jul. 20, 1995.

The present invention relates to novel azo dyes of the formula I##STR2## where

R¹ and R² are independently of each other C₁ -C₁₀ -alkyl with or withoutsubstitution by cyano, hydroxyl, halogen, C₁ -C₄ -alkanoyloxy, C₁ -C₄-alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyloxy or phenyl and with or withoutinterruption by from 1 to 4 oxygen atoms in ether function, C₅ -C₇-cycloalkyl, C₃ -C₄ -alkenyl, unsubstituted or C₁ -C₄ -alkyl-, C₁ -C₄-alkoxy- or halogen-substituted phenyl, or R¹ and R² are together withthe nitrogen atom joining them together a 5- or 6-membered saturatedheterocyclic radical with or without further hetero atoms,

R³ is tert-butyl or tert-pentyl, and

D is a radical of a diazo component of the aniline series or the seriesof the aromatic heterocyclic amines,

a process for the thermal transfer of these dyes and to their use fordyeing or printing synthetic materials.

EP-A-441 208 discloses azo dyes with a 2-aminothiazole as couplingcomponent.

It is an object of the present invention to provide novel azo dyes whichhave advantageous application properties in the dyeing or printing oftextile materials or in thermal dye transfer.

We have found that this object is achieved by the azo dyes of theformula I defined at the beginning.

Emphasis is given to azo dyes of the formula I where D is derived from adiazo component of the aniline series or from an amine of the pyrrole,thiophene, pyrazole, thiazole, isothiazole, triazole, thiadiazole,benzothiophene, benzothiazole, benzisothiazole, pyridothiophene,pyrimidothiophene or thienothiophene series.

Suitable radicals D conform for example to the formula ##STR3## where

L¹ is nitro, cyano, C₁ -C₆ -alkanoyl, benzoyl, C₁ -C₆ -alkoxycarbonyl,C₁ -C₈ -alkylsulfonyl, substituted or unsubstituted phenylsulfonyl or aradical of the formula --CH═T, where T is hydroxyimino, C₁ -C₄-alkoxyimino or a radical of an acidic-CH compound H₂ T,

L² is hydrogen, C₁ -C₆ -alkyl, halogen, hydroxyl, mercapto,unsubstituted or phenyl- or C₁ -C₄ -alkoxy-substituted C₁ -C₆ -alkoxy,substituted or unsubstituted phenoxy, unsubstituted orphenyl-substituted C₁ -C₈ -alkylthio, substituted or unsubstitutedphenylthio, C₁ -C₉ -alkylsulfonyl or substituted or unsubstitutedphenylsulfonyl,

L³ is cyano, C₁ -C₆ -alkoxycarbonyl or nitro,

L⁴ is hydrogen, C₁ -C₆ -alkyl or phenyl,

L⁵ is C₁ -C₆ -alkyl or phenyl,

L⁶ is hydrogen, cyano, nitro, C₁ -C₆ -alkoxycarbonyl, C₁ -C₆ -alkanoyl,thiocyanato or halogen,

L⁷ is nitro, cyano, C₁ -C₆ -alkanoyl, benzoyl, C₁ -C₆ -alkoxycarbonyl,C₁ -C₈ -alkylsulfonyl, substituted or unsubstituted phenylsulfonyl or aradical of the formula --CH═T, where T is as defined above,

L⁸ is hydrogen, C₁ -C₆ -alkyl, substituted or unsubstituted phenyl,cyano, halogen, unsubstituted or phenyl- or C₁ -C₄ -alkoxy-substitutedC₁ -C₈ -alkoxy, unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio,substituted or unsubstituted phenylthio, C₁ -C₈ -alkylsulfonyl,substituted or unsubstituted phenylsulfonyl or C₁ -C₆ -alkoxycarbonyl,

L⁹ is cyano, unsubstituted or phenyl- or C₁ -C₄ -alkoxy- substituted C₁-C₆ -alkyl, unsubstituted or phenyl-substituted C₁ -C₈ -alkoxy,unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio, substituted orunsubstituted phenyl, thienyl, C₁ -C₄ -alkylthienyl, pyridyl or C₁ -C₄-alkylpyridyl or, together with L⁶, a fused benzo radical,

L¹⁰ is phenyl or pyridyl,

L¹¹ is trifluoromethyl, nitro, C₁ -C₆ -alkyl, phenyl, unsubstituted orphenyl-substituted C₁ -C₈ -alkylthio or C₁ -C₆ -dialkylamino,

L¹² is unsubstituted or acetyloxy-substituted C₁ -C₆ -alkyl, phenyl,unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio, 2-cyanoethylthioor 2-(C₁ -C₆ -alkoxycarbonyl)ethylthio,

L¹³ is hydrogen, nitro or halogen,

L¹⁴ is hydrogen, cyano, C₁ -C₆ -alkoxycarbonyl, nitro or halogen,

L¹⁵, L¹⁶ and L¹⁷ are independently of each other hydrogen, C₁ -C₆-alkyl, C₁ -C₆ -alkoxy, halogen, nitro, cyano, unsubstituted orphenoxy-substituted C₁ -C₆ -alkoxycarbonyl, C₁ -C₈ -alkylsulfonyl orsubstituted or unsubstituted phenylsulfonyl, or L¹⁵ and L¹⁶ are togethera radical of the formula CO--NW--CO where W is C₁ -C₁₀ -alkyl with orwithout interruption by 1 or 2 oxygen atoms in ether function and withor without substitution by hydroxyl,

L¹⁸ is hydrogen, methyl or chlorine, and

L¹⁹ is cyano or C₁ -C₆ -alkoxycarbonyl.

Any alkyl or alkenyl appearing in the abovementioned formulae may bestraight-chain or branched.

In any substituted alkyl appearing in the abovementioned formulae thenumber of substituents is generally 1 or 2.

Any substituted phenyl appearing in the abovementioned formulae may haveas substituents for example, unless otherwise mentioned, C₁ -C₈ -alkyl,C₁ -C₈ -alkoxy, halogen, especially chlorine or bromine, or nitro.

In any substituted phenyl, furanyl or thienyl appearing in theabovementioned formulae the number of substituents is generally from 1to 3, preferably 1 or 2.

L², L⁴, L⁵, L⁸, L⁹, L¹¹, L¹², L¹⁵, L¹⁶, L¹⁷, R¹, R² and W are each forexample methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl,tert-butyl, pentyl, isopentyl, neopentyl, tert-pentyl, hexyl or2-methylpentyl.

R¹, R², R⁶ and W may each also be for example heptyl, occyl,2-ethylhexyl, isooctyl, nonyl, isononyl, decyl or isodecyl (thedesignations isooctyl, isononyl and isodecyl are trivial names derivedfrom the oxo process alcohols--cf. Ullmann's Encyclopedia of IndustrialChemistry, 5th Edition, Vol. A 1, pages 290 to 293, and Vol. A 10, pages284 and 285).

R¹, R² and R⁶ may each also be for example cyclopentyl,methylcyclopentyl, dimethylcyclopentyl, cyclohexyl, methylcyclohexyl orcycloheptyl.

L⁹, R¹, R² and W may each also be for example 2-methoxyethyl,2-ethoxyethyl, 2-propoxyethyl, 2-isopropoxyethyl, 2-butoxyethyl, 2- or3-methoxypropyl, 2- or 3-ethoxypropyl, 2- or 3-propoxypropyl, 2- or3-butoxypropyl, 2- or 4-methoxybutyl, 2- or 4-ethoxybutyl, 2- or4-propoxybutyl or 2- or 4-butoxybutyl.

R¹, R² and W may each also be for example 3,6-dioxaheptyl,3,6-dioxaoctyl, 4,8-dioxanonyl, 3,7-dioxaoctyl, 3,7-dioxanonyl,4,7-dioxaoetyl, 4,7-dioxanonyl or 4,8-dioxadecyl.

R¹ and R² may each also be for example 3,6,8-trioxadecyl,3,6,9-trioxaundecyl, 3,6,9,12-tetraoxatridecyl,3,6,9,12-tetraoxatetradecyl, 2-cyanoethyl, 2- or 3-cyanopropyl, 2- or4-cyanobutyl, 2-hydroxyethyl, 2- or 3-hydroxypropyl, 2- or4-hydroxybutyl, 2-chloroethyl, 2- or 3-chloropropyl, 2- or4-chlorobutyl, 2-acetyloxyethyl, 2- or 3-acetyloxypropyl, 2- or4-acetyloxybutyl, 2-propionyloxyethyl, 2- or 3-propionyloxypropyl, 2- or4-propionyloxybutyl, 2-methoxycarbonylethyl, 2-ethoxycarbonylethyl,2-propoxycarbonylethyl, 2-isopropoxycarbonylethyl,2-butoxycarbonylethyl, 2- or 3-methoxycarbonylpropyl, 2- or3-ethoxycarbonylpropyl, 2- or 3-propoxycarbonylpropyl, 2- or3-butoxycarbonylpropyl, 2- or 4-methoxycarbonylbutyl, 2- or4-ethoxycarbonylbutyl, 2- or 4-propoxycarbonylbutyl, 2- or4-butoxycarbonylbutyl, 2-methoxycarbonyloxyethyl,2-ethoxycarbonyloxyethyl, 2-propoxycarbonyloxyethyl,2-isopropoxycarbonyloxyethyl, 2-butoxycarbonyloxyethyl, 2- or3-methoxycarbonyloxypropyl, 2- or 3-ethoxycarbonyloxypropyl, 2- or3-propoxycarbonyloxypropyl, 2- or 3-butoxycarbonyloxypropyl, 2- or4-methoxycarbonyloxybutyl, 2- or 4-ethoxycarbonyloxybutyl, 2- or4-propoxycarbonyloxybutyl, 2- or 4-butoxycarbonyloxybutyl,prop-1-en-3-yl, but-2-en-4-yl or 2-methylprop-1-en-3-yl.

L⁹, R¹ and R² may each also be for example benzyl or 1- or2-phenylethyl.

L¹² may also be for example 2-acetyloxyethyl, 2- or 3-acetyloxypropyl or2- or 4-acetyloxybutyl.

L², L⁸, L⁹ and L¹¹ may each also be for example methylthio, ethylthio,propylthio, isopropylthio, butylthio, isobutylthio, pentylthio,hexylthio, heptylthio, octylthio, 2-ethylhexylthio, benzylthio or 1- or2-phenylethylthio.

L² and L⁸ may each also be for example phenylthio, 2-methylphenylthio,2-methoxyphenylthio or 2-chlorophenylthio.

L², L⁸, L⁹, L¹⁵, L¹⁶ and L¹⁷ may each also be for example methoxy,ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, pentyloxy,isopentyloxy, neopentyloxy, tert-pentyloxy, hexyloxy or2-methylpentyloxy.

L⁹ may also be for example benzyloxy or 1- or 2-phenylethoxy.

L⁶ is and each of L², L⁸, L¹³, L¹⁴, L¹⁵, L¹⁶ and L¹⁷ may further also befor example fluorine, chlorine or bromine.

L⁷ and L¹ are each and each of L², L⁸, L¹⁵, L¹⁶ and L¹⁷ may further alsobe for example methylsulfonyl, ethylsulfonyl, propylsulfonyl,isopropylsulfonyl, butylsulfonyl, isobutylsulfonyl, sec-butylsulfonyl,pentylsulfonyl, isopentylsulfonyl, neopentylsulfonyl, hexylsulfonyl,heptylsulfonyl, octylsulfonyl, 2-ethylhexylsulfonyl, phenylsulfonyl,2-methylphenylsulfonyl, 2-methoxyphenylsulfonyl or2-chlorophenylsulfonyl.

L³ is and each of L¹, L⁶, L⁷, L⁸, L¹⁴, L¹⁵, L¹⁶, L¹⁷ and L¹⁹ may furtheralso be for example methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl,isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl,sec-butoxycarbonyl, pentyloxycarbonyl, isopentyloxycarbonyl,neopentyloxycarbonyl or hexyloxycarbonyl.

L¹⁵, L¹⁶ and L¹⁷ may each also be for example 2-phenoxyethoxycarbonyl,2- or 3-phenoxypropoxycarbonyl or 2- or 4-phenoxybutoxycarbonyl.

L² and L⁸ may each also be for example 2-methoxyethoxy, 2-ethoxyethoxy,2- or 3-methoxypropoxy, 2- or 3-ethoxypropoxy, 2- or 4-methoxybutoxy, 2-or 4-ethoxybutoxy, 5-methoxypentyloxy, 5-ethoxypentyloxy,6-methoxyhexyloxy, 6-ethoxyhexyloxy, benzyloxy or 1- or 2-phenylethoxy.

L¹¹ may also be for example dimethylamino, diethylamino, dipropylamino,diisopropylamino, dibutylamino, dipentylamino, dihexylamino orN-methyl-N-ethylamino.

L¹² may also be for example 2-methoxycarbonylethylthio or2-ethoxycarbonylethylthio.

L⁸, L⁹, R¹ and R² may each also be for example phenyl, 2-, 3- or4-methylphenyl, 2,4-dimethylphenyl, 2-, 3- or 4-methoxyphenyl, 2-, 3- or4-chlorophenyl or 2-, 3- or 4-nitrophenyl.

L⁹ may also be for example 2- or 3-methylthienyl or 2-, 3- or4-methylpyridyl.

L¹, L⁶ and L⁷ may each also be for example formyl, acetyl, propionyl,butyryl, isobutyryl, pentanoyl or hexanoyl.

In a --CH═T radical L¹ or L⁹ where T is derived from an acidic-CHcompound H₂ T said acidic CH compound H₂ T can for example be a compoundof the formula ##STR4## where

Z¹ is cyano, nitro, C₁ -C₄ -alkanoyl, substituted or unsubstitutedbenzoyl, C₁ -C₄ -alkylsulfonyl, substituted or unsubstitutedphenylzulfonyl, C₁ -C₄ -alkoxycarbonyl, C₃ -C₄ -alkenyloxycarbonyl,phenoxycarbonyl, carbamoyl, mono- or di(C₁ -C₄ -alkyl)carbamoyl,substituted or unsubstituted phenylcarbamoyl, substituted orunsubstituted phenyl, 2-benzothiazolyl, 2-benzimidazolyl,5-phenyl-1,3,4-thiadiazol-2-yl or 2-hydroxy-3-quinoxalinyl,

Z² is C₁ -C₄ -alkyl, C₁ -C₄ -alkoxy or C₃ -C₄ -alkenyloxy,

Z³ is C₁ -C₄ -alkoxycarbonyl, C₃ -C₄ -alkenyloxycarbonyl,phenylcarbamoyl or 2-benzimidazolyl,

Z⁴ is cyano, C₁ -C₄ -alkoxycarbonyl or C₃ -C₄ -alkenyloxycarbonyl,

Z⁵ is hydrogen or C₁ -C₆ -alkyl,

Z⁶ is hydrogen, C₁ -C₄ -alkyl or phenyl, and

Z⁷ is C₁ -C₄ -alkyl.

Attention is drawn to the radical derived from compounds of the formulaIIIa, IIIb or IIIc where Z¹ is cyano, C₁ -C₄ -alkanoyl, C₁ -C₄-alkoxycarbonyl or C₃ -C₄ -alkenyloxycarbonyl, Z² is C₁ -C₄ -alkyl, C₁-C₄ -alkoxy or C₃ -C₄ -alkenyloxy, Z³ is C₁ -C₄ -alkoxycarbonyl or C₃-C₄ -alkenyloxycarbonyl and Z⁴ is cyano.

Particular attention is drawn to the radical derived from compounds ofthe formula IIIa, IIIb or IIIc where Z¹ is cyano, C₁ -C₄ -alkoxycarbonylor C₃ -C₄ -alkenyloxycarbonyl, Z² is C₁ -C₄ -alkoxy or C₂ -C₄-alkenyloxy, Z³ is C₁ -C₄ -alkoxycarbonyl or C₃ -C₄ -alkenyloxycarbonyland Z⁴ is cyano.

R¹ and R¹ combined with the nitrogen atom joining them together into afive- or six-membered saturated heterocyclic radical with or withoutfurther hetero atoms may be for example pyrrolidinyl, piperidinyl,morpholinyl, thiomorpholinyl, thiomorpholinyl S,S-dioxide, piperazinylor N-(C₁ -C₄ -alkyl)piperazinyl, such as N-methyl- orN-ethyl-piperazinyl.

Preference is given to azo dyes of the formula I where R¹ and R² areindependently of each other C₁ -C₈ -alkyl which may be C₁ -C₄ -alkoxy-,C₁ -C₄ -alkoxycarbonyl- or phenyl-substituted, cyclopentyl, cyclohexylor prop-1-en-3-yl.

Preference is further given to azo dyes of the formula I where D is aradical of the formula IIb, IId, IIe, IIh or IIq.

Particular preference is given to azo dyes of the formula I where R¹ andR² are independently of each other C₁ -C₆ -alkyl with or withoutsubstitution by phenyl.

Particular preference is further given to azo dyes of the formula Iwhere R³ is tert-butyl.

Particular preference is further given to azo dyes of the formula Iwhere D is a radical of the formula IIb, IId, IIe, IIh or IIq where

L¹ is nitro, cyano, formyl or a radical of the formula --CH═T where T isa radical of an acidic-CH compound H₂ T,

L² is C₁ -C₆ -alkyl or halogen,

L³ is cyano, C₁ -C₆ -alkoxycarbonyl or nitro,

L⁶ is cyano,

L⁷ is nitro, cyano, formyl, C₁ -C₆ -alkoxycarbonyl or a radical of theformula --CH═T where T is as defined above,

L⁸ is C₁ -C₆ -alkyl, substituted or unsubstituted phenyl, cyano, halogenor C₁ -C₆ -alkoxycarbonyl,

L⁹ is unsubstituted or phenyl-substituted C₁ -C₆ -alkyl, unsubstitutedor phenyl-substituted C₁ -C₆ -alkylthio or substituted or unsubstitutedphenyl,

L¹² is unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio, and

L¹⁵, L¹⁶ and L¹⁷ are independently of one another hydrogen, C₁ -C₆-alkyl, C₁ -C₆ -alkoxy, nitro, cyano or unsubstituted orphenoxy-substituted C₁ -C₆ -alkoxycarbonyl, or L¹⁵ and L¹⁶ are togethera radical of the formula CO--NW--CO where W is as defined above.

The novel azo dyes of the formula I can be obtained in a conventionalmanner, for example by conventionally diazotizing a diazo component ofthe formula IV

    D--NH.sub.2                                                (IV),

where D is as defined above, and coupling the resulting diazonium saltwith an aminothiazole of the formula V ##STR5##

where R¹, R² and R³ are each as defined above.

The present invention further provides a process for transferring dyesfrom a transfer to plastic-coated paper by diffusion or sublimation bymeans of an energy source, which comprises using a transfer on whichthere is or are one or more azo dyes of the formula I.

To make the transfers required for the process of the present invention,the azo dyes of the formula I are incorporated in a suitable organicsolvent or a mixture of solvents with one or more binders with orwithout auxiliaries to form a printing ink. This printing ink preferablycontains the dyes in a molecularly disperse, ie. dissolved, form. Theprinting ink can be applied to the inert support by means of a doctorblade and air dried. Suitable organic solvents for the azo dyes of theformula I include for example those in which the solubility of the dyesat a temperature of 20° C. is greater than 1% by weight, preferablygreater than 5% by weight.

Examples are ethanol, propanol, isobutanol, tetrahydrofuran, methylenechloride, methyl ethyl ketone, cyclopentanone, cyclohexanone, toluene,chlorobenzene or mixtures thereof.

Suitable binders include all resins or polymer materials which aresoluble in organic solvents and which are capable of binding the azodyes to the inert support sufficiently firmly as to prevent rubbing off.Preference is given to those binders which, after the air drying of theprinting ink, include the dyes in the form of a clear, transparent filmwithout any visible crystallization of the dyes.

Such binders are mentioned for example in U.S. Pat. No. 5,132,438 or thepertinent patent applications cited therein. Also suitable are saturatedlinear polyesters.

Preferred binders include ethylcellulose, ethylhydroxyethylcellulose,polyvinyl butyral, polyvinyl acetate, cellulose propionate or saturatedlinear polyesters.

The weight ratio of binder:azo dye generally ranges from 1:2 to 4:1.

Suitable auxiliaries include for example release agents as mentioned inU.S. Pat. No. 5,132,438 or the pertinent patent applications citedtherein. Also suitable are especially organic additives which preventthe crystallizing out of the transfer dyes in the course of storage oron heating of the color ribbon, for example cholesterol or vanillin.

Suitable inert supports are described for example in U.S. Pat. No.5,132,438 or the pertinent patent applications cited therein. Thethickness of the support generally ranges from 3 to 30 μm, preferablyfrom 5 to 10 μm.

Suitable dye receiver layers include in principle all thermally stableplastics layers with affinity for the dyes to be transferred, forexample modified polycarbonates or polyesters. Further details can befound for example in U.S. Pat. No. 5,132,438 or the pertinent patentapplications cited therein.

The transfer is effected by means of an energy source, for example bymeans of a laser or a thermal head, for which the latter has to beheatable to a temperature of ≧300° C. so that the transfer of the dyecan take place within the time range t: 0<t<15 msec. The dye migratesout of the transfer sheet and diffuses into the surface coating of thereceiving medium.

The azo dyes of the formula I of the present invention are notable foradvantageous application properties. They exhibit high solubility in thecolor ribbon (good compatibility with the binder), a high stability inthe printing ink, good transfer-ability and high image stability (ie.good lightfastness and also good stability to environmental effects, forexample moisture, temperature or chemicals), and permit flexiblecoloristic adaptation to given subtractive primary colors as part of anoptimal trichromat (dye mixture).

The novel dyes are also suitable for use as components for blackmixtures.

They are also notable in some instances for high brilliance owing to thehigh transparency in the blue and red parts of the spectrum.

The azo dyes of the formula I of the present invention are alsoadvantageously suitable for dyeing or printing synthetic materials, forexample polyesters, polyamides or polycarbonates. Of particularsuitability are textile materials, such as fibers, yarns, threads,knits, wovens or nonwovens in polyester, modified polyester, eg.anionically modified polyester, or blends of polyesters with cellulose,cotton, viscose or wool. The dyeing and printing conditions are knownper se. The dyes according to the invention can also be used for dyeingkeratinous fibers, for example in hair dyeing or the dyeing of skins.

The novel azo dyes of the formula I are also advantageously useful forpreparing color filters as described for example in EP-A-399 473.

Finally, they can also be used with advantage as dyes for use inelectrophotographic toners.

The Examples which follow illustrate the invention.

A) Preparation

EXAMPLE 1

22.2 g of 3-methyl-4-cyano-5-aminoisothiazole were suspended in 150 mlof 7:3 v/v glacial acetic acid/propionic acid. 6 ml of concentratedsulfuric acid were added, followed at from 0° to 5° C. by the dropwiseaddition of 48 g of nitrosylsulfuric acid. The mixture was subsequentlystirred at from 0° to 50° C. for 3 h. The diazonium salt solution wasthen added dropwise at from 0° to 5° C. into a solution of 52 g of2-dibutylamino-4-tert-butylthiazole (82.9% strength by weight) in 100 mlof N,N-dimethylformamide This was followed by buffering with 20 g ofsodium acetate. The batch was subsequently stirred at room temperature,and the precipitate was filtered off with suction, washed with methanoland water and dried to leave 55.8 g (83.5% of theory) of the dye of theformula ##STR6##

mp.: 202° C.; λ_(max) (in THF); 527 nm

EXAMPLE 2

5.2 g of 2,5-dichloro-4-nitroaniline were suspended in 10 g of 96%strength by weight sulfuric acid at from 20° to 30° C. and then admixedat from 15° to 20° C. with 13 g of nitrosylsulfuric acid. This resultingsolution was added to 50 ml of water and 100 g of ice, and the batch wassubsequently stirred for 15 min and filtered. The filtrate was addeddropwise at from 0° to 5° C. to a solution of 9.3 g of2-dibutylamino-4-tert-butylthiazole in 100 ml of methanol. Afterstirring overnight at room temperature, the precipitate was filtered offwith suction, washed with methanol and water and dried to leave 9.58 g(78.8% of theory) of the dye of the formula ##STR7##

mp.: 164° C.; λ_(max) (in THF): 522 nm

EXAMPLE 3

5.2 g of dimethyl 2-aminoterephthalate were suspended in 25 ml ofglacial acetic acid and 10 ml of concentrated hydrochloric acid andadmixed at from 0° to 5° C. with 8 ml of 23% strength by weight aqueoussodium nitrite solution. The batch was subsequently stirred at from 0°to 5° C. for 1 h and then added at from 0° to 5° C. to a solution of 9.2g of 2-dibutylamino-4-tert-butylthiazole in 200 ml of methanol. Afterbuffering with 10 g of sodium acetate, the batch was stirred andfiltered, and the filter residue was washed with methanol and water anddried to leave 6.23 g (51% of theory) of the dye of the formula ##STR8##

mp.: 74° C.; λ_(max) (in THF): 462 nm

The same method can be used to obtain the dyes listed below in Table 1.

                                      TABLE 1                                     __________________________________________________________________________     ##STR9##                                                                                                            λ.sub.max                       Ex.                                     nm!                                   No.                                                                              D                 X.sup.1                                                                              X.sup.2    (in CH.sub.2 Cl.sub.2)                 __________________________________________________________________________     4                                                                                ##STR10##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 587                                     5                                                                                ##STR11##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 632                                     6                                                                                ##STR12##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 631                                     7                                                                                ##STR13##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 528                                     8                                                                                ##STR14##        C(CH.sub.3).sub.3                                                                    N(CH.sub.2 C.sub.6 H.sub.5).sub.2                                                        524                                     9                                                                                ##STR15##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 535                                    10                                                                                ##STR16##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 514                                    11                                                                                ##STR17##        C(CH.sub.3).sub.3                                                                    N CH(CH.sub.3).sub.2 !.sub.2                                                             497                                    12                                                                                ##STR18##        C(CH.sub.3).sub.3                                                                    N(CH.sub.3).sub.2                                                                        485                                    13                                                                                ##STR19##        CH(CH.sub.3).sub.3                                                                   N(C.sub.4 H.sub.9).sub.2                                                                 516                                    14                                                                                ##STR20##        C(CH.sub.3).sub.3                                                                    N(C.sub.3 H.sub.7).sub.2                                                                 516                                    15                                                                                ##STR21##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5)                                                                       517                                    16                                                                                ##STR22##        C(CH.sub.3).sub.3                                                                    N(CH.sub.3).sub.2                                                                        509                                    17                                                                                ##STR23##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 521                                    18                                                                                ##STR24##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 498                                    19                                                                                ##STR25##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 513                                    20                                                                                ##STR26##        C(CH.sub.3).sub.3                                                                    N(CH.sub.2 C.sub.6 H.sub.5).sub.2                                                        527                                    21                                                                                ##STR27##        C(CH.sub.3).sub.3                                                                    N(C.sub.3 H.sub.7).sub.2                                                                 524                                    22                                                                                ##STR28##        C(CH.sub.3).sub.3                                                                    N(CH.sub.3).sub.2                                                                        528                                    23                                                                                ##STR29##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 528                                    24                                                                                ##STR30##        C(CH.sub.3).sub.3                                                                     ##STR31## 533                                    25                                                                                ##STR32##        C(CH.sub.3).sub.3                                                                     ##STR33## 531                                    26                                                                                ##STR34##        C(CH.sub.3).sub.3                                                                     ##STR35## 533                                    27                                                                                ##STR36##        C(CH.sub.3).sub.3                                                                     ##STR37## 527                                    28                                                                                ##STR38##        C(CH.sub.3).sub.3                                                                     ##STR39## 528                                    29                                                                                ##STR40##        C(CH.sub.3).sub.3                                                                     ##STR41## 528                                    30                                                                                ##STR42##        C(CH.sub.3).sub.3                                                                     ##STR43## 541                                    31                                                                                ##STR44##        C(CH.sub.3).sub.3                                                                     ##STR45## 527                                    32                                                                                ##STR46##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 518                                    33                                                                                ##STR47##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 550                                    34                                                                                ##STR48##        C(CH.sub.3).sub.3                                                                    N(CH.sub.3).sub.2                                                                        463                                    35                                                                                ##STR49##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 535                                    36                                                                                ##STR50##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 531                                    37                                                                                ##STR51##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 537                                    38                                                                                ##STR52##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 533                                    39                                                                                ##STR53##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 531                                    40                                                                                ##STR54##        C(CH.sub.3).sub.3                                                                    N(CH.sub.2 C.sub.6 H.sub.5).sub.2                                                        515                                    41                                                                                ##STR55##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 515                                    42                                                                                ##STR56##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 528                                    43                                                                                ##STR57##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 531                                    44                                                                                ##STR58##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 514                                    45                                                                                ##STR59##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 515                                    46                                                                                ##STR60##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 512                                    47                                                                                ##STR61##        C(CH.sub.3).sub.3                                                                     ##STR62## 524                                    48                                                                                ##STR63##        C(CH.sub.3).sub.3                                                                     ##STR64## 529                                    49                                                                                ##STR65##        C(CH.sub.3).sub.3                                                                    N(C.sub.3 H.sub.7).sub.2                                                                 531                                    50                                                                                ##STR66##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 515                                    51                                                                                ##STR67##        C(CH.sub.3).sub.3                                                                     ##STR68## 524                                    52                                                                                ##STR69##        C(CH.sub.3).sub.3                                                                     ##STR70## 527                                    53                                                                                ##STR71##        C(CH.sub.3).sub.3                                                                     ##STR72## 528                                    54                                                                                ##STR73##        C(CH.sub.3).sub.3                                                                     ##STR74## 528                                    55                                                                                ##STR75##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 480                                    56                                                                                ##STR76##        C(CH.sub.3).sub.3                                                                    N(CH.sub.3).sub.2                                                                        454                                    57                                                                                ##STR77##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 648                                    58                                                                                ##STR78##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 481                                    59                                                                                ##STR79##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 460                                    60                                                                                ##STR80##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 460                                    61                                                                                ##STR81##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 468                                    62                                                                                ##STR82##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 456                                    63                                                                                ##STR83##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 544                                    64                                                                                ##STR84##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 506                                    65                                                                                ##STR85##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 490                                    66                                                                                ##STR86##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 491                                    67                                                                                ##STR87##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 543                                    68                                                                                ##STR88##        C(CH.sub.3).sub.3                                                                     ##STR89## 541                                    69                                                                                ##STR90##        C(CH.sub.3).sub.3                                                                    N(C.sub.3 H.sub.7).sub.2                                                                 542                                    70                                                                                ##STR91##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 535                                    71                                                                                ##STR92##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 528                                    72                                                                                ##STR93##        C(CH.sub.3).sub.3                                                                    N(C.sub.2 H.sub.5).sub.2                                                                 548                                    73                                                                                ##STR94##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 524                                    74                                                                                ##STR95##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 558                                    75                                                                                ##STR96##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                                                                 576                                    76                                                                                ##STR97##        C(CH.sub.3).sub.2 C.sub.2 H.sub.5                                                    N(C.sub.2 H.sub.5).sub.2                          77                                                                                ##STR98##        C(CH.sub.3).sub.3                                                                    N(C.sub.4 H.sub.9).sub.2                          __________________________________________________________________________

B) Use in thermal transfer

Method for thermal transfer

a) 10 g of dye are stirred, if necessary with brief heating to 80°-90°C., into 100 g of a 10% strength by weight solution of a binder in4.5:2:2 v/v/v methyl ethyl ketone/toluene/cyclohexanone.

The mixture is applied with a 6 μm doctor blade to a 6 μm thickpolyester film which has a suitable slipping layer on the back and isblown dry with a hair dryer in the course of 1 minute. Before the colorribbon can be printed, it has to be air dried for at least a further 24hours, since residual solvent can impair the printing process.

b) The color ribbons are printed on an experimental computer-controlledapparatus equipped with a commercial thermal printing head ontocommercial color videoprint paper (Hitachi).

The voltage is altered to control the energy emitted by the thermalprinting head, the length of a pulse having been set to 7 ms and onlyone pulse being emitted at a time. The emitted energy level ranges from0.7 to 2.0 mJ/dot.

Since the depth of the color is directly proportional to the suppliedenergy, it is possible to use a color wedge for spectroscopicevaluation.

The depth of the color is plotted against the supplied energy perheating element to determine the Q* value (=energy in mJ for theabsorbance value of 1) and the gradient m in 1/mJ.

The results obtained are shown together with the λ_(max) values(measured on the videoprint paper) below in Table 2.

The binder used in each case was a product based on a saturated linearpolyester and on polyvinyl butyral, the first value of Q* and m in thetable for each example being measured with the polyester as binder andthe second with polyvinyl butyral as binder.

                  TABLE 2                                                         ______________________________________                                                  Q*             m      λ.sub.max                              Dye No.    mJ/Dot!        l/mJ!  nm!                                          ______________________________________                                        1         0.87           3.00   534                                                     0.93           2.40                                                 4         1.05           2.17   582                                                     1.07           2.31                                                 5         1.20           1.75   637                                                     1.32           1.06                                                 7         0.89           2.96   531                                                     1.02           1.78                                                 8         1.38           1.38   528                                                     1.84           0.82                                                 9         0.89           2.86   540                                                     0.95           2.30                                                 10        1.00           1.22   518                                                     0.99           2.11                                                 11        1.00           1.97   492                                                     1.10           1.69                                                 12        0.99           2.05   485                                                     1.07           1.85                                                 13        0.99           2.02   540                                                     0.97           2.08                                                 14        0.86           2.70   520                                                     0.94           2.40                                                 15        0.78           2.80   515                                                     0.94           3.56                                                 16        1.01           2.01   515                                                     1.13           1.74                                                 17        0.89           3.70   523                                                     1.01           2.63                                                 18        0.91           3.29   502                                                     0.98           2.60                                                 19        0.92           3.12   515                                                     1.01           2.50                                                 20        0.92           2.80   530                                                     0.98           2.50                                                 21        0.89           2.14   527                                                     1.13           1.71                                                 23        0.86           3.12   534                                                     0.87           3.12                                                 24        0.96           2.20   537                                                     1.07           1.95                                                 25        0.87           3.03   537                                                     0.92           2.59                                                 26        0.92           2.24   537                                                     0.99           2.32                                                 27        0.86           2.85   535                                                     0.85           2.79                                                 28        0.85           3.34   531                                                     0.90           3.21                                                 29        0.85           3.14   532                                                     0.90           3.04                                                 30        0.87           2.85   549                                                     1.01           2.04                                                 31        0.91           3.00   531                                           32        0.79           2.74   518                                           33        0.83           3.63   554                                           34        1.02           2.06   458                                           35        0.90           2.56   536                                                     0.89           2.42                                                 36        0.88           2.87   535                                                     0.92           2.50                                                 37        0.92           2.56   540                                                     0.92           2.20                                                 38        0.90           2.68   536                                                     0.90           2.71                                                 39        0.88           2.34   537                                                     0.95           2.28                                                 40        1.10           1.61   518                                                     1.07           1.66                                                 41        0.89           2.65   514                                                     0.96           2.08                                                 42        0.85           2.88   529                                                     0.92           2.85                                                 43        0.86           3.39   531                                                     0.86           3.36                                                 44        0.91           2.26   516                                                     0.96           2.34                                                 45        0.90           2.44   520                                                     l.02           2.01                                                 46        0.95           2.44   514                                                     0.99           2.31                                                 47        0.87           3.43   531                                                     0.93           2.75                                                 48        0.95           2.38   534                                                     0.92           2.65                                                 49        0.90           2.98   534                                                     0.96           2.45                                                 50        0.86           3.14   515                                                     0.88           3.04                                                 51        0.92           2.48   527                                                     0.96           2.61                                                 52        1.04           1.89   531                                                     1.15           1.66                                                 53        0.83           3.25   530                                                     0.90           2.93                                                 54        0.81           4.30   531                                                     0.88           3.07                                                 55        0.96           2.35   476                                                     1.04           2.09                                                 56        0.88           2.71   446                                                     0.97           2.40                                                 57        1.17           1.45   654                                           58        0.91           2.48   477                                                     1.00           2.09                                                 59        1.05           1.66   445                                                     1.12           1.46                                                 60        1.04           1.54   459                                                     1.08           1.70                                                 61        1.14           1.53   440                                                     1.17           1.66                                                 62        1.31           1.30   441                                                     1.37           1.13                                                 63        0.91           3.11   550                                           64        0.86           3.09   508                                                     0.94           2.63                                                 65        0.86           2.87   489                                                     0.94           2.42                                                 66        0.82           3.61   494                                                     0.83           3.11                                                 67        0.87           3.14   546                                                     0.94           2.66                                                 68        0.87           2.85   549                                                     1.01           2.04                                                 69        0.94           2.38   545                                           70        0.89           2.86   540                                                     0.95           2.30                                                 71        0.89           2.86   531                                                     1.02           1.78                                                 72        0.79           3.33   552                                                     0.89           2.77                                                 73        0.84           2.92   524                                                     0.91           2.28                                                 74        0.86           2.54   563                                                     0.94           2.49                                                 75        0.82           4.01   582                                                     0.87           2.98                                                 76        0.86           3.40                                                 ______________________________________                                    

c) Use in dyeing

10 g of polyester fabric are introduced at a temperature of 50° C. into200 ml of a dyeing liquor which contains X% by weight, based on fiber,of dye and whose pH has been adjusted to 4.5 with acetic acid. After 5min at 50° C., the temperature of the liquor is raised over 30 min to130° C., held at that level for 60 min and then brought back down over20 min to 60° C.

The dyed polyester fabric is then reduction cleared by treating it at65° C. for 15 min in 200 ml of a liquor containing 5 ml/l of 32%strength by weight sodium hydroxide solution, 3 g/l of sodium dithioniteand 1 g/l of an addition product of 48 mol of ethylene oxide with 1 molof castor oil. Finally the fabric is rinsed, neutralized with diluteacetic acid, rinsed once more and dried.

Dyes 1 and 20 gave the following results:

Dye 1

Dye quantity (X): 0.26% by weight

HGD: 358.9

Chroma: 54

Light fastness; 6-7

Dye 20

Dye quantity (X): 0.29% by weight

HGD: 351.7

Chroma: 54.9

Light fastness: 6-7

We claim:
 1. An Azo dye of the formula I ##STR99## where R¹ and R² areindependently of each other C₁ -C₁₀ -alkyl with or without substitutionby cyano, hydroxyl, halogen, C₁ -C₄ -alkanoyloxy, C₁ -C₄-alkoxycarbonyl, C₁ -C₄ -alkoxycarbonyloxy or phenyl and with or withoutinterruption by from 1 to 4 oxygen atoms in ether function, C₅ -C₇-cyloalkyl, C₃ -C₆ -alkenyl, unsubstituted or C₁ -C₄ -alkyl-, C₁ -C₄-alkoxy- or halogen-substituted phenyl, or R¹ and R² are together withthe nitrogen atom joining them together a 5- or 6-membered saturatedheterocyclic radical with or without further hetero atoms,R³ istert-butyl or tert-pentyl, and D is a radical of a diazo component ofthe aniline series or the series of the aromatic heterocyclic amines. 2.The azo dye as claimed in claim 1 wherein D is derived from a diazocomponent of the aniline series or from an amine of the pyrrole,thiophene, pyrazole, thiazole, isothiazole, triazole, thiadiazole,benzothiophene, benzothiazole, benzisothiazole, pyridothiophene,pyrimidothiophene or thienothiophene series.
 3. The azo dye as claimedin claim 1 wherein D is a radical of the formula ##STR100## where L¹ isnitro, cyano, C₁ -C₆ -alkanoyl, benzoyl, C₁ -C₆ -alkoxycarbonyl, C₁ -C₈-alkylsulfonyl, substituted or unsubstituted phenylsulfonyl or a radicalof the formula --CH═T, where T is hydroxyimino, C₁ -C₄ -alkoxyimino or aradical of an acidic-CH compound H₂ T,L² is hydrogen, C₁ -C₆ -alkyl,halogen, hydroxyl, mercapto, unsubstituted or phenyl- or C₁ -C₄-alkoxy-substituted C₁ -C₆ -alkoxy, substituted or unsubstitutedphenoxy, unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio,substituted or unsubstituted phenylthio, C₁ -C₉ -alkylsulfonyl orsubstituted or unsubstituted phenylsulfonyl, L³ is cyano, C₁ -C₆-alkoxycarbonyl or nitro, L⁴ is hydrogen, C₁ -C₆ -alkyl or phenyl, L⁵ isC₁ -C₆ -alkyl or phenyl, L⁶ is hydrogen, cyano, nitro, C₁ -C₆-alkoxycarbonyl, C₁ -C₆ -alkanoyl, thiocyanato or halogen, L⁷ is nitro,cyano, C₁ -C₆ -alkanoyl, benzoyl, C₁ -C₆ -alkoxycarbonyl, C₁ -C₈-alkylsulfonyl, substituted or unsubstituted phenylsulfonyl or a radicalof the formula --CH═T, where T is as defined above, L⁸ is hydrogen, C₁-C₆ -alkyl, substituted or unsubstituted phenyl, cyano, halogen,unsubstituted or phenyl- or C₁ -C₄ -alkoxy-substituted C₁ -C₆ -alkoxy,unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio, substituted orunsubstituted phenylthio, C₁ -C₈ -alkylsulfonyl, substituted orunsubstituted phenylsulfonyl or C₁ -C₆ -alkoxycarbonyl, L⁹ is cyano,unsubstituted or phenyl- or C₁ -C₄ -alkoxy-substituted C₁ -C₆ -alkyl,unsubstituted or phenyl-substituted C₁ -C₈ -alkoxy, unsubstituted orphenyl-substituted C₁ -C₈ -alkylthio, substituted or unsubstitutedphenyl, thienyl, C₁ -C₄ -alkylthienyl, pyridyl or C₁ -C₄ -alkylpyridyl,L¹⁰ is phenyl or pyridyl, L¹¹ is trifluoromethyl, nitro, C₁ -C₆ -alkyl,phenyl, unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio or C₁ -C₆-dialkylamino, L¹² is unsubstituted or acetyloxy-substituted C₁ -C₆-alkyl, phenyl, unsubstituted or phenyl-substituted C₁ -C₈ -alkylthio,2-cyanoethylthio or 2-(C₁ -C₆ -alkoxycarbonyl)ethylthio, L¹³ ishydrogen, nitro or halogen, L¹⁴ is hydrogen, cyano, C₁ -C₆-alkoxycarbonyl, nitro or halogen, L¹⁵, L¹⁶ and L¹⁷ are independently ofeach other hydrogen, C₁ -C₆ -alkyl, C₁ -C₆ -alkoxy, halogen, nitro,cyano, unsubstituted or phenoxy-substituted C₁ -C₆ -alkoxycarbonyl, C₁-C₈ -alkylsulfonyl or substituted or unsubstituted phenylsulfonyl, orL¹⁵ and L¹⁶ are together a radical of the formula CO--NW--CO where W isC₁ -C₁₀ -alkyl with or without interruption by 1 or 2 oxygen atoms inether function and with or without substitution by hydroxyl, L¹⁸ ishydrogen, methyl or chlorine, and L¹⁹ is cyano or C₁ -C₆-alkoxycarbonyl.
 4. The azo dye as claimed in any of claims 1 to 3wherein R¹ and R² are independently of each other C₁ -C₈ -alkyl whichmay be C₁ -C₄ -alkoxy-, C₁ -C₄ -alkoxycarbonyl- or phenyl-substituted,cyclopentyl, cyclohexyl or prop-1-en-3-yl.
 5. The azo dye as claimed inclaim 3 wherein D is a radical of the formula IIb, IId, IIe, IIh or IIq.6. The azo dye as claimed in claim 1 wherein R¹ and R² are independentlyof each other C₁ -C₆ -alkyl with or without substitution by phenyl. 7.The azo dye as claimed in claim 1 wherein R³ is tert-butyl.
 8. The azodye as claimed in claim 3 wherein D is a radical of the formula IIb,IId, Ie, IIh or IIq whereL¹ is nitro, cyano, formyl or a radical of theformula --C═T where T is a radical of an acidic-CH compound H₂ T, L² isC₁ -C₆ -alkyl or halogen, L³ is cyano, C₁ -C₆ -alkoxycarbonyl or nitro,L⁶ is cyano, L⁷ is nitro, cyano, formyl, C₁ -C₆ -alkoxycarbonyl or aradical of the formula --CH═T where T is as defined above, L⁸ is C₁ -C₆-alkyl, substituted or unsubstituted phenyl, cyano, halogen or C₁ -C₆-alkoxycarbonyl, L⁹ is unsubstituted or phenyl-substituted C₁ -C₆-alkyl, unsubstituted or phenyl-substituted C₁ -C₆ -alkylthio orsubstituted or unsubstituted phenyl, L¹² is unsubstituted orphenyl-substituted C₁ -C₈ -alkylthio, and L¹⁵, L¹⁶ and L¹⁷ areindependently of one another hydrogen, C₁ -C₆ -alkyl, C₁ -C₆ -alkoxy,nitro, cyano or unsubstituted or phenoxy-substituted C₁ -C₆-alkoxycarbonyl, or L¹⁵ and L¹⁶ are together a radical of the formulaCO--NW--CO where W is as defined in claim
 3. 9. An azo dye of theformula ##STR101## wherein R¹ and R² are each independently a C₁₋₁₀alkyl; R³ is tert-butyl;L⁶ is cyano; and L⁹ is cyano, unsubstituted orphenyl- or C₁₋₄ alkoxy-substituted C₁₋₁₆ alkyl, unsubstituted orphenyl-substituted C₁₋₈ alkoxy, unsubstituted or phenyl-substituted C₁₋₈alkylthio, substituted or unsubstituted phenyl, thienyl, C₁₋₄alkylthienyl, pyridyl or C₁₋₄ alkylpyridyl, or together with L⁶, a fusedbenzo radical.
 10. A process for transferring dyes from a transfer toplastic-coated paper by diffusion or sublimation by means of an energysource, which comprises using a transfer on which there is or are one ormore azo dyes as claimed in claim
 1. 11. A method of dyeing or printinga synthetic material, comprising applying the azo dye of claim 1 to asynthetic material.